scaffold tasks extension

Empty skeleton mirroring the events extension layout: config/manifest,
pyproject + Makefile + ruff/mypy config, FastAPI routers wired into
tasks_ext, NostrClient bootstrap stubs, and an empty static/routes.json.

Models, migrations, CRUD, Nostr publisher/sync, and the API/template
layers land in follow-up commits.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Makefile

@@ -0,0 +1,32 @@
+all: format check
+
+format: black ruff
+
+check: mypy checkblack checkruff
+
+mypy:
+	uv run mypy .
+
+black:
+	uv run black .
+
+ruff:
+	uv run ruff check . --fix
+
+checkruff:
+	uv run ruff check .
+
+checkblack:
+	uv run black --check .
+
+test:
+	PYTHONUNBUFFERED=1 \
+	DEBUG=true \
+	uv run pytest
+
+install-pre-commit-hook:
+	@echo "Installing pre-commit hook to git"
+	uv run pre-commit install
+
+pre-commit:
+	uv run pre-commit run --all-files